1. Field of the Invention
The invention pertains to the mechanical coupling of solid metallic connectors to solid or compacted metallic conductors and more particularly to the termination or coupling of solid or compacted aluminum or solid or compacted copper conductors to provide good mechanical strength and high electrical conductivity between such conductors and connectors.
2. Description of the Prior Art
According to the prior art solid and stranded conductors of aluminum and copper are joined to similar conductors or terminated in connectors of similar metals, i.e. aluminum conductors to aluminum conductors using aluminum splicers or aluminum conductors to aluminum terminators--by crimping or compacting the metal of the connector and the metal of the conductor, inserted into a suitable bore in the connector, into as compacted and solid a mass as possible. The crimping may be by the use of circular dies which compress the metal mass uniformly over the entire perimeter of the compression zone or by hexagonal nested dies with their own compression pattern. If the hardness of the conductor and connector are the same and the modulus of elasticity is the same and there is no springback, the compressed mass will remain the way it was when the compression was completed.
However, if the conductor is harder than the connector, the crimping tool will not deform the conductor and the conductor can be withdrawn from the connector. Conversely, if the connector is harder than the conductor, the connector would exhibit a springback due to the original hardness of the connector itself which would try to return to its former state resulting in an incomplete mechanical and a high-impedance electrical connection between the conductor and connector.
In U.S. Pat. No. 3,033,600 issued May 8, 1962, a sleeve or insert 3 is placed upon the end of a wire 7 inserted into the bore in a shell 1. The insert 3 is hollow and split partially as by the use of slots 6. The outer surface of insert 3 is formed with serrations 4 and a screwthreaded interior surface 5. The shell 1, insert 3 and wire 7 are assembled by cold swagging "in a hydraulic press or other suitable apparatus furnished with appropriately-shaped dies, the pressing being completed in one or more operations depending upon the capacity of the press available."As a result "the projections of the internal screwthreads 5 of the inserts 3 to bite into or grip the wires 7 to be joined, the inserts themselves being retained in the sleeve 1 because of the knurling, serrations or the like 4 co-acting with the bores of the sleeve to form indentations therein . . . the ends of the sleeve 1 are upset or contoured into close proximity or engagement with the wires 7 to form a substantially weatherproof seal and still further increase the efficiency of the connector."
The patent is only concerned with the mechanical joining of wires, rods and the like and not the electrical coupling of conductors and connectors and no mention is made of the electrical properties of the joint. Further, no mention is made of the relative hardness and springiness of the component parts.
U.S. Pat. No. 3,184,535 issued May 18, 1965 is similar to the '600 patent but includes multiple bores, each intended to handle one portion of a multi-part wire. For example, in FIG. 1, sleeve 1 has smaller diameter bores adjacent midfeather 5 to handle the cable cores and larger diameter bores adjacent the sleeve 1 ends to accommodate the surrounding cable strands. Each bore accepts a suitably sized insert 2 formed similarly to that described in the '600 patent and the overall device is also similarly assembled in a suitable tool.
In U.S. Pat. No. 3,996,417 issued Dec. 7, 1976, a core grip 4 having external lobes 6 (see FIGS. 2 and 3) is used to couple the core 14 of a core reinforced cable 10, the strands 12 of which are gripped by the wall 22 of a compression barrel 20 into which cable 10 is inserted.
No mention is made in the '535 or '417 patents of the needs of an electrically conductive joint nor is there any mention made of the relative hardness or springiness of the cable, core, strands, insert or shell.